1. Field of the Invention
The present invention relates to an air conditioning unit employing liquid absorbent such as lithium bromide as collection means of vaporized refrigerant such as vapor of water.
2. Description of Prior Art
An air conditioning unit for producing cold air utilizing vaporization of refrigerant and absorbing the vaporized refrigerant by liquid absorbent is called as an absorption type air conditioning unit. That is, in case that water is used as a refrigerant, when water is dropped in the atmosphere inside the condenser kept under low pressure or in a vacuum state, water absorbs heat from the periphery thereof and evaporates instantaneously. Heat required for the evaporation is a so-called latent heat. Media such as water and air are forcibly circulated using the latent heat as a cooling source for performing heat exchange to produce cold air, which is permitted to flow in a room, thereby cooling the room.
In such an air conditioning unit, as the refrigerant which is evaporated in an evaporator is condensed and returned to the evaporator, liquid absorbent such as lithium bromide is employed. That is, the refrigerant evaporated in the evaporator is absorbed by the liquid absorbent in an absorber and collected. When the liquid absorbent is heated after it is stored in a liquid tank and the refrigerant is evaporated, the refrigerant vapor is separated from the liquid absorbent to concentrate the liquid absorbent and the refrigerant vapor is condensed and liquefied, then it is returned to the refrigerant tank while the liquid absorbent from which the refrigerant is separated is returned to the absorber.
There are prior applications relating to this type of air conditioning units each employing an absorption refrigerating machine which are disclosed in JP-A 7-103597, JP-A 7-103600, JP-A 7-103601, JP-A 7-103602, JP-A 7-103603, JP-A 7-110171, JP-A 7-158995, and there is a prior application relating to a method of separating refrigerant in an air conditioning unit disclosed in JP-A 7-332799.
Whereupon, in such an air conditioning unit, when cooling operation stops, lithium bromide may crystallize owing to the decrease of an outside-air temperature. When lithium bromide crystallizes in lines or an air conditioning unit, the liquid absorbent is prevented from flowing, thereby putting the air conditioning unit out of operation. If there is no means to cope with this situation, the air conditioning unit is liable to operate improperly, deteriorating reliability of the air conditioning unit.
Although crystallized lithium bromide can be liquefied when it is heated, there are limitations in countermeasures or prevention of lithium bromide crystallization resorting to provision of heating means in the entire lines for liquefaction of the crystallized lithium bromide, because such provision increases installation cost. Further, it is not efficient from the structural point of view to detect crystallized portions and to heat that portion locally.